ENH: cleanup of line_covered, make sure strings are not truncated (mo…

[nno]

This should get rid of the (harmless) message during compilation of mocov_line_covered.c.

mocov_line_covered.c:191:48: warning: ‘%s’ directive output may be truncated writing up to 98 bytes into a region of size between 2 and 100 [-Wformat-truncation=]
  191 |     snprintf(error_id, MAX_ERROR_ID_LENGTH, "%s%s", ERROR_ID_PREFIX,
      |                                                ^~
In file included from /usr/include/stdio.h:980,
                 from mocov_line_covered.c:23:
In function ‘snprintf’,
    inlined from ‘raise_mex_error’ at mocov_line_covered.c:191:5:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:54:10: note: ‘__snprintf_chk’ output between 1 and 197 bytes into a destination of size 100
   54 |   return __builtin___snprintf_chk (__s, __n, __USE_FORTIFY_LEVEL - 1,
      |          ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   55 |                                    __glibc_objsize (__s), __fmt,
      |                                    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   56 |                                    __va_arg_pack ());
      |                                    ~~~~~~~~~~~~~~~~~

Also, a few tweaks on the comments.

[nno]

This is Work In Progress - there still is a warning message I have to look into. Please do not merge yet.

[nno]

With some small changes the warning message is not shown anymore.

[nno]

@jorgepz @Remi-Gau I didn't see a review yet. That's totally fine, but if there are no objections --- and since all checks pass, and the changes are minor --- I would like to merge into the main branch soon-ish.

[jorgepz]

go on! thanks